Influence factors of asymmetrical local energy dissipation in current-carrying microcircuit

Abstract

As miniaturization being an irreversible trend of modern electronic devices, nanoscale thermal management becomes increasingly important. Local heat dissipation causes large thermal gradients on small length scales in microelectronics devices, resulting in serious performance problems. Local heat dissipation origins from thermally excited terahertz waves (wavelength between 8 μm and 25 μm) on material surface caused by thermal fluctuation due to electron movements and lattice vibrations. A home-made Scanning Near-field Optical Microscope (SNOM), equipped with the terahertz detector named CSIP (charge-sensitive infrared phototransistor), is utilized to map nanoscale microcircuit heat distribution. The ultrahigh sensitive CSIP makes direct detection at room temperature without external illumination possible. Previous study visualized nanoscale heat dissipation on current-carrying Nichrome (NiCr) wires and found localized “hot-spot” developing along narrow wires or sharp corners of bended wires, which is consistent with the current-crowding effect. This research aims to further conclude influence factors of the asymmetrical distribution of “hot-spot” in microcircuits, which lacks sufficient experiments and explanation. Finite Element Method simulation of Joule heating on microcircuit suggests that the inhomogeneous current density distribution caused by electrode bias could be a reason of hot-spot asymmetry. NiCr microcircuits with both biased and unbiased electrode are expected to fabricate for control experiments.